Seismic prospecting method and device using a drill bit working in a well

摘要

The method consists in performing seismic prospecting operations by using a drill bit (1) working at the bottom of a well (2), which generates very powerful acoustic jogs, in transmitting in real time or in delayed time reference signals representative of the jogs of the drill bit picked up in the immediate vicinity thereof by bottomhole sensors and in correlating the seismic signals picked up by a reception set with the reference signals coming from the bottom. The reference signals may be transmitted to the surface station through a line (4) included in a drill string (3). Absorbing elements are preferably interposed on the string to damp the vibrations propagating directly towards the surface along the drill string. Resonant elements and possibly acoustic discontinuity elements favouring resonances in the seismic frequency band may also be interposed.